Changes in the lower respiratory epithelia induced by oestrogen intake. An experimental histopathological study.

Fifty-eight male and non-pregnant female guinea pigs with an average weight of 400 gm were used in this work, ten animals as a control group, the remaineder receiving oestrogen in the form of ethanyl oestradiol in a dose of 10 microgram/animal/day. Histopathological studies were carried out after periods of one, two, three, four and eight weeks, and three, six and twelve months respectively. The respiratory mucosa, at the different levels mentioned, showed definite changes. The surface epithelium showed metaplastic changes with mitotic figures, until complete and definite stratifications were reached. The cilia decreased and then disappeared completely, while the mucus-secreting goblet cells showed an initial augmentation in number and increased activity, followed by a gradual decrease in their number, until total disappearance occurred at the stage of stratification in the surface epithelium.